The transport mechanisms at localized states of thin films of GexAsySe1-x-y chalcogenide glasses under off-equilibrium conditions

Abstract

The resistance of chalcogenide glass GexAsySe1-x-y film is difficult to be observed due to the electrons pinned near the Fermi level, the large electron binding energy, and the large film resistance. Because the resistance is too large, the test method of Hall effect cannot be used to investigate the electrical properties for chalcogenide glass. In this work, the resistance relaxation states of a series of GexAsySe1-x-y films with different components are observed by reducing the resistance under non-equilibrium temperature conditions from 300 to 440 K, and then the local state electron transport mechanism is investigated. It is interesting that the electrical properties parameters show three relaxation states: 1) The conventional trend is that the conductivity decreases with the increase of temperature. 2) One particular trend is that the resistance presents a wavy shape as the temperature increases. 3) The most special trend is that as the temperature is raised during the conductivity measurements, the conductivity increases before decreases after having reach a certain temperature. Computer calculation results show that the Boltzmann fit formula is more suitable than simply Boltzmann formula for GexAsySe1-x-y chalcogenide film in terms of a low-mobility semiconductor with deep Fermi level and hopping conduction. Through calculations, it is found that three relaxation states are decided by the density of the localized states at Fermi level. Show more